Cell to heat sink thermal adhesive

Abstract

A battery module includes a housing having an opening and an electrochemical cell disposed in the housing. The electrochemical cell includes a first cell surface having electrode terminals and an second cell surface substantially opposite the first cell surface. The battery module also includes a heat sink integral with the housing and a thermally conductive adhesive bonded to the second cell surface and a heat sink surface that is facing the second cell surface. The thermally conductive adhesive can include a bonding shear strength and bonding tensile strength between the electrochemical cell and the heat sink of between approximately 5 megaPascals (MPa) and 50 MPa.

What is claimed is: 
     
       1. A battery module comprising:
 a housing comprising a first material; 
 an electrochemical cell disposed in the housing, the electrochemical cell comprising a first cell surface having electrode terminals and a second cell surface substantially opposite the first cell surface; 
 a heat sink integral with a portion of the housing and comprising a second material different from the first material, the heat sink having a heat sink surface facing the second cell surface; 
 a thermally conductive adhesive configured to bond the second cell surface and the heat sink surface, the thermally conductive adhesive comprising a mixture of an epoxy resin and a hardener, with the epoxy resin having a viscosity between approximately 40,000 centipoise (cP) and approximately 50,000 cP at 25 degrees centigrade and with the hardener having a second viscosity of between greater than 35,000 cP and 50,000 cP at 25° C.; and 
 the thermally conductive adhesive having a bonding shear strength and a bonding tensile strength between the electrochemical cell and the heat sink of between approximately 5 megaPascals (MPa) and approximately 50 MPa at 25 degrees Celsius. 
 
     
     
       2. The battery module of  claim 1 , wherein the mixture is configured to cure in less than or equal to approximately 24 hours. 
     
     
       3. The battery module of  claim 1 , wherein the mixture comprises a weight ratio of between approximately 1:1 and approximately 2:1 epoxy resin to hardener. 
     
     
       4. The battery module of  claim 1 , wherein the portion of the housing is a base portion disposed substantially opposite an opening of the housing. 
     
     
       5. The battery module of  claim 1 , wherein the thermally conductive adhesive comprises a radiation-activated epoxy resin. 
     
     
       6. The battery module of  claim 1 , wherein the thermally conductive adhesive comprises a thermal conductivity between approximately 0.5 Watt/meter Kelvin (W/mK) and approximately 2.0 W/mK. 
     
     
       7. The battery module of  claim 1 , wherein the thermally conductive adhesive is self-leveling. 
     
     
       8. The battery module of  claim 1 , wherein the thermally conductive adhesive has a working life of between approximately 1 hour and approximately 3 hours. 
     
     
       9. The battery module of  claim 1 , wherein the thermally conductive adhesive comprises a hardness equal to approximately 80 Shore D. 
     
     
       10. The battery module of  claim 1 , further comprising an additional electrochemical cell disposed in the housing, wherein the additional electrochemical cell comprises a third cell surface having electrode terminals and a fourth cell surface substantially opposite the third cell surface, wherein a gap is formed between the electrochemical cell and the additional electrochemical cell in the housing, and wherein the thermally conductive adhesive extends into the gap such that the thermally conductive adhesive is configured to conform to the electrochemical cell and the additional electrochemical cell to compensate for variability in dimensions of the electrochemical cell and the additional electrochemical cell. 
     
     
       11. The battery module of  claim 1 , wherein the thermally conductive adhesive having a coefficient of thermal expansion between 0.5 ppm/degrees Celsius and 40 ppm/degrees Celsius. 
     
     
       12. A battery module, comprising:
 a plurality of electrochemical cells secured to a heat sink coupled to a housing of the battery module, wherein the heat sink extends in at least one direction to an outermost dimension of the housing, and wherein each electrochemical cell of the plurality of electrochemical cells is in secured connection with the heat sink; and 
 a thermally conductive adhesive positioned at an interface between the plurality of electrochemical cells and the heat sink, wherein; 
 the thermally conductive adhesive comprising an epoxy resin and a hardener, with the epoxy resin having a viscosity between approximately 40,000 centipoise (cP) and approximately 50,000 cP at 25 degrees centigrade and with the hardener having a second viscosity of between greater than 35,000 cP and 50,000 cP at 25° C.; and 
 the thermally conductive adhesive providing for the secured connection of the plurality of electrochemical cells with the heat sink at the interface, with the thermally conductive adhesive having a bonding shear strength and a bonding tensile strength between the plurality of electrochemical cells and the heat sink of between approximately 5 megaPascals (MPa) and approximately 50 MPa at 25 degrees Celsius. 
 
     
     
       13. The battery module of  claim 12 , wherein the thermally conductive adhesive has a thermal conductivity between approximately 0.5 Watt/meter Kelvin (W/mK) and approximately 2.0 W/mK. 
     
     
       14. The battery module of  claim 12 , wherein the thermally conductive adhesive comprises a mixture of the epoxy resin and the hardener. 
     
     
       15. The battery module of  claim 14 , wherein the mixture has a weight ratio of between approximately 1:1 and 2:1 epoxy resin to hardener. 
     
     
       16. The battery module of  claim 12 , wherein the thermally conductive adhesive has a hardness equal to approximately 80 Shore D after curing. 
     
     
       17. The battery module of  claim 12 , wherein a thickness of the thermally conductive adhesive along the interface is substantially uniform after curing. 
     
     
       18. The battery module of  claim 12 , wherein the thermally conductive adhesive is self-leveling. 
     
     
       19. The battery module of  claim 12 , wherein the thermally conductive adhesive has a working life of between approximately 1 hour and approximately 3 hours. 
     
     
       20. The battery module of  claim 12 , wherein the thermally conductive adhesive having a coefficient of thermal expansion between 0.5 ppm/degrees Celsius and 40 ppm/degrees Celsius.